The 802.11 protocol suite defined by the Institute of Electrical and Electronics Engineers (Institute of Electrical and Electronics Engineers, IEEE) is standards of a wireless local area network (Wireless local Access Network, WLAN). Existing WLAN standards based on an orthogonal frequency division multiplexing (Orthogonal Frequency Division Multiplexing, OFDM) technology include progressively evolving standards, such as 802.11a, 802.11n, and 802.11ac, and are still continuously evolving. As the WLAN develops and gradually gains popularity, a situation in which WLAN devices supporting different standards coexist will be long-standing. To implement backward compatibility, a wireless access point (AP) and a Station (STA) that use a new-generation standard both need to be capable of supporting use of a previous standard.
Because different frame formats are used in existing multiple WLAN standards and a future WLAN standard, a WLAN device that uses a new-generation standard needs to have a capability of identifying frames of different WLAN standards.